Shebang at top of javascript files is not preserved

[BrianSipos]

I have a project with some javascript entrypoints containing a top line of

#!/usr/bin/env node

which seems to be a common (but maybe not well specified) extension to allow shell shebang lines with javascript. I can point to examples of use in many NPM packages, but it seems like this is a node ability to handle and not an ECMAScript standard ability.

It would be good if the licenseheaders tool preserved these top line shebangs the same way they are preserved for shell, python, etc. types of files when inserting the copyright header.